The use of slides with stringed musical instruments has long been known. Generally speaking, the slide has one straight edge that is long enough to bridge a number of strings of the instrument at one time. By using the slide, the person playing the instrument can depress a number of strings at the same time, and thereby shorten the length of the strings, change their vibration frequency, and hence change the musical character of the instrument. But the slide is used only on an interim basis, and when it is not being used the instrument has its original musical character.
One feature of all the many slides with which I have been familiar is that the player loses the use of one or more fingers while applying the slide to the strings. Thus, if the player is plucking the strings, as with the guitar, the loss of finger availability restricts the musical performance that can be rendered.